c# 读写web.config配置文件的方法

public static void writeConfig(string item, string key, string value)
{
if (item == "")
{
item = "appSettings";
}
Configuration config = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration(System.Web.HttpContext.Current.Request.ApplicationPath);
AppSettingsSection appSection = (AppSettingsSection)config.GetSection(item);
if (appSection.Settings[key] == null)
{
appSection.Settings.Add(key, value);
config.Save();
}
else
{
appSection.Settings.Remove(key);
appSection.Settings.Add(key, value);
config.Save();
}
}